28 One-Design Class Sailboat Handbook 



for hull strength but for water integrity. While this type of construction 

 is very durable, it requires recalking and considerable maintenance. 

 Because of these disadvantages, carvel is the least popular for boat con- 

 struction. 



Strip-planking is a type of carvel construction that is commonly used 

 on many boats today. Strip-planking utilizes a method similar to tongue- 

 and-groove matching with a sealer in the seams. Generally speaking, strip- 

 planking produces inexpensive, lightweight, sleek and sturdy hulls, but it 

 requires a good deal of maintenance to keep it in top shape. 



Plywood Sailboats. Plywood craft utilize two types of material: the sheet 

 and the molded. In recent years, sheet plywood has largely taken the place 

 of wood-planked hulls in smaller sailboats. This type of construction re- 

 quires a framework or skeleton similar to that in carvel-planked boats 

 except perhaps for somewhat fewer frames. But because big plywood 

 panels will cover wide areas they shorten construction time, reduce the 

 seam area and the number of fastenings required. Cross-grained bonding 

 of the veneers makes a construction material that is splitproof, virtually 

 punctureproof and dimensionally stable. This means greater strength 

 with less weight at a sizable reduction in cost. Joints are end-butted and 

 glued so that calking troubles are reduced to a minimum. The principal 

 drawback of plywood hulls is the bending limitation of the material, 

 which controls the degree of sharpness to which the planking may be 

 curved. 



Sheet-plywood hulls are easy to repair. Simply fit in a new square of 

 plywood of the size needed, backed up by any necessary battens to prevent 

 leaking; or in the case of less severe damage, leave the injured piece in, 

 covering it with a butt block from the inside. Being of a wood product, 

 plywood hulls require scraping and painting. 



All modern plywood boats aren't built of sheet plywood. The molded- 

 plywood hull was introduced just before World War II and is still used 

 in the manufacture of smaller boats. In this manufacturing process, the 

 hull is "planked" upside down over a solid wood mold. Each "plank" 

 consists of a single ply, and has been previously cut to shape from a pat- 

 tern, to fit its exact place on the boat. The "planks" are laid on diagonally, 

 stapled to the mold. Then waterproof glue (resin glue of the hot-press 

 type) is applied. Next comes another layer of piles or "plank," diagonally 



